Soil Sensors

Soil conditions are important drivers of biogeochemical processes and biological activity in the soil, which in turn influence ecosystem properties including plant growth and ecosystem carbon exchange. To better understand these linkages automated sensors continuously monitor a range of soil properties at terrestrial sites.

NEON installs an array of five soil plots within the flux tower’s footprint and in the locally dominant (~1 km2 scale) soil type of each terrestrial field site. Spacing between soil plots was determined by assessing spatial variation in soil temperature and moisture over ~1 hectare  to maximize spatial independence, while being constrained to ≤40 m due to cost constraints.

Vertical profiles of soil temperature (≤9 sensors per plot), moisture (≤8 sensors per plot), and CO2 concentration (3 sensors per plot) are measured in each plot, with measurement depths based on soil depth, soil horizon thicknesses, and other soil properties. Heat flux is measured near the soil surface in three of the soil plots. All soil sensor measurements are made at 0.1 Hz. In addition, radiation and throughfall measurements are made near the soil surface.

Why These Soil Measurements?

These soil properties, extending from the soil surface down to 2 m deep, are relevant to short-term predictions, such as flood or heat wave risk, as well as biological activity, including soil respiration rates and plant growth. For example, soil respiration data can be used to partition ecosystem-level carbon exchange into above- and below-ground components, while soil moisture data can provide a contextual understanding of temporal variation in plant production. Similarly, time series of radiation and throughfall measurements near the soil surface can be directly related to phenological events (e.g., leaf out and litterfall). Read on to learn more about other soil measurements and samples that NEON collects.

Data Products

Soil Sensor Data

  • Soil CO2 concentration
  • Soil temperature
  • Soil water content and salinity (soil moisture)
  • Soil heat flux

Meteorological Data Collected at Soil Plots

These data are also collected at the tower unless otherwise noted.

  • Relative humidity
  • IR biological temperature
  • Photosynthetically active radiation - Quantum Line
  • Net longwave radiation
  • Precipitation/Throughfall (only at the soil array)

Learn more about NEON’s meteorological data collection.

Additional Higher Level Data Products

These planned data products will be created in collaboration with Ameriflux, and are derived from a variety of data including measurements collected at the soil array.

  • Temporally Interpolated Soil Temperature
  • Temporally Interpolated Biological Temperature
  • Temporally interpolated Photosynthetically Active Radiation
  • Temporally Interpolated PAR-Line
  • Temporally Interpolated Shortwave and Longwave Radiation (Net radiometer)

Explore NEON Data

Related Soil Measurements

In addition to automated data collection through the soil array, NEON field scientists collect soil samples for biogeochemical analysis and to archive. They also collect soil microbe observations. The resulting data products include:

Biogeochemical

  • Soil chemical properties (Megapit)
  • Soil chemical properties (Distributed initial characterization)
  • Soil chemical properties (Distributed periodic)
  • Soil inorganic nitrogen pools and transformations
  • Soil stable isotopes (Distributed periodic)

Physical

  • Soil physical properties (Megapit)
  • Soil physical properties (Distributed initial characterization)
  • Soil physical properties (Distributed periodic)

Organismal

  • Soil microbes (biomass, community composition, and group abundances)
  • Soil microbe marker genes and metagenomes

Related Archival Samples

NEON collects, processes and archives a variety of soils and soil microbes from each terrestrial field site.

  • Soils for physical and chemical measurements (collected periodically)
  • Megapit soils (collected once during initial site characterization)
  • Excess soils
  • Soils: DNA extractions
  • Soil microbes (frozen): organic and mineral horizons, maximum sample depth 30 cm

Explore NEON Archival Samples

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